JavaScript Object.freeze()

Definition and usage

Object.freeze() The method is used to prevent any changes to the object.

In non-strict mode,Object.freeze() The method will fail silently.

In strict mode,Object.freeze() The method will throw a TypeError.

Frozen objects are read-only. Modifications, additions, or deletions of properties are not allowed.

Can be used Object.isFrozen() Methods to check if an object is frozen.

Related methods:

Object.preventExtensions() Modification is allowed, but adding properties is prevented.

Object.seal() Allows modification, but prevents addition and deletion of properties.

Object.freeze() Prevents modification, addition, and deletion of properties.

Object.isExtensible() Returns true if the object is extensible.

Object.isSealed() Returns true if the object is sealed.

Object.isFrozen() Returns true if the object is frozen.

Instance

Example 1

"use strict"
// Create an object
const person = {
  firstName: "Bill",
  lastName: "Gates",
  age: 50,
  eyeColor: "blue"
};
// Freeze the object
Object.freeze(person);
// This will throw an error
person.age = 51;

Try It Yourself

Example 2

const fruits = ["Banana", "Orange", "Apple", "Mango"];
Object.freeze(fruits);
// This will throw an error:
fruits.push("Kiwi");

Try It Yourself

Syntax

Object.freeze(object)

Parameter

Return Value

Browser Support

Object.freeze() Is a feature of ECMAScript5 (ES5).

Since July 2013, all modern browsers have fully supported ES5 (JavaScript 2009):